Good question. After a couple of attempts, notably with Ford, Mazda signed an agreement with Toyota in 2015.So Mazda isn’t a “major” brand?
toyota-mazda-form-partnership-to-share-technologies-confront-cost-challenges
So in 2017 they signed a deal with Toyota and Denso for BEV
Mazda, Denso, and Toyota Sign Joint Technology Development Contract for Electric Vehicles | Toyota Motor Corporation Official Global Website
Mazda Motor Corporation (Mazda), Denso Corporation (Denso), and Toyota Motor Corporation (Toyota) signed a contract today to jointly develop basic structural technologies for electric vehicles. Furthermore, the three companies have also decided to establish a new company consisting of selected...
global.toyota